1. Field of the Invention
The present invention relates generally to salt, pepper and granular, powdery, or other particle condiment dispensers. More particularly, the present invention relates to sprayers utilizing air pressure within a container to eject particles stored within the container to form a spray of air and suspended particles.
2. Description of the Prior Art
The common and readily available salt and pepper shaker, as well as similar structures for other condiments, are well known. The salt and pepper, hereinafter referred to generally as particulate material, are stored within a container and poured from the container onto food through a pattern of holes in a top of the container. The principal drawback to the common device is the inability to measure even reasonably precisely the amount of particulate material to be deposited onto the food. In addition, material is easily spilled if the common devices are turned over or upset for any reason.
U.S. Pat. No. 2,609,971 to M. Vivolo shows a salt dispenser in which salt flows by gravity into an air passage in a small but uncontrolled accumulation. Squeezing a bulb generates a pulse of compressed air, which flows through the passage and carries the salt out of the dispenser. Vivolo incorporates a storage area with a convex bottom having a hole at the lowermost position for the feeding of the particulate material through the hole and into the passage. The passage communicates with the bulb to receive compressed air to force the particulate material through a projecting nipple for dispensing onto the food.
The difficulty with Vivolo, as well as all of the prior art using air pressure to force particulate material along a passage, is that the air which flows along the passage must force the material directly from the dispenser. This process has three drawbacks. Firstly, the passage is more likely to be clogged by the particulate material as some material is pushed by air pressure, while other material is moved by collisions with the material directly influenced by air pressure. Secondly, the particulate material is not necessarily dispersed evenly into the spray of air by the pulse of air generated. Thirdly, it is not likely that any preselected amount of particulate material will be dispensed, since the volume of the passage available for a pulse of air is not controlled nor controllable.
Italian Patent No. 449,894 is also a sprayer utilizing a piston and bellows to eject particulate material from the device. As in Vivolo the material is deposited into a passage and then air pressure is used to eject the material. A linkage meters the particulate material into the passage tube.
U.S. Pat. No. 3,785,568 to E. Pfingsten passes a gaseous fluid at pressure through a tube which intersects and communicates with a second depending tube. The depending tube extends into a reservoir of material. The passage of the gaseous fluid develops a low pressure area in the depending tube which causes the material to be elevated into the gaseous fluid stream and carried away. Pfingsten does not use direct air pressure to move particulate material and therefore defines a more evenly dispersed spray. However, Pfingsten still moves material with direct air pressure down a common feed tube, which is more likely to be clogged.
U.S. Pat. No. 2,126,924 to W. Rose is a dust sprayer utilizing a manually operated plunger to force air through openings over one end of a tube. The other end of the tube communicates with a dust filled zone above powder stored in a container. The air flow generated by the plunger over the openings generates a low pressure zone, which draws dust up the tube. The same plunger action forces air down another tube and through a powder body to enhance the efficiency of the sprayer by creating a dust cloud into which the first tube depends. Rose is similar to Pfingsten in using high velocity air, created by a plunger, to draw powder into a tube by creating a low pressure zone.
U.S. Pat. No. 4,120,427 to J. McRoskey, et al. shows a powder container including an annular air channel through which air is forced by the action of a diaphragm. This action reduces the volume of the container. Venturi openings connect the interior of the container with a channel which allows powder to be drawn into the channel and exhausted through a discharge nozzle.
U.S. Pat. No. 1,554,991 to J. Crowley forces air through a nozzle to draw powder from a reservoir. Crowley uses gravity in combination with air pressure to move the powder.
U.S. Pat. No. 2,202,079 to W. Ayres shows a dispenser for powder which employs air flow through tubes to generate suction at venturi locations, drawing powder into the air flow for transport out of the dispenser. Again, positive air pressure, rather than negative or low pressure, is used to move the material.
U.S. Pat. No. 2,358,329 to E. Houghton compresses air in a chamfer by depression of a member, forcing air through a tube, past a slot and to a tube exit. The slot communicates with powder in a container. The passage of the high pressure air over the slot draws powder into the air stream under the influence of the low pressure thereby created.
U.S. Pat. No. 3,904,087 to J. McRoskey, et al. uses a longitudinally extending tube with spaced venturi openings to pull powder into an air stream passing vertically upward through the tube. Squeezing and releasing an outer container forces the material from an inner container into the tube, through a nozzle, ejecting the material from the device.
My copending patent, U.S. Pat. No. 4,896,833, is similar to the present invention. However, that patent does not control air flow after a piston has been activated to spray the particulate material.